Fig. 7. Effects of interfering with BMP signalling on the distribution of transcripts known to be involved in NR and RPE development. (A-D) Control experiments overexpressing a viral RCAS (B) (labelled RCAS-B) construct only (parallel sections). (A) Eye morphology is normal following viral infection with RCAS (B). Expression of the viral reverse transcriptase gene (RT) indicates infected areas of the RPE (arrows). (B) In the eyes infected with RCAS (B), Otx2 expression is still restricted to the RPE (arrowheads) and no transcripts are observed in the NR at stage 20. (C) Following viral injection of RCAS (B), MMP115 expression is unchanged and is restricted to the RPE (arrowheads). (D) Expression of the NR-specific marker Chx10 is not observed in the outer layer of the optic cup following injection of RCAS (B) (arrowheads). (E-H) The effects following injection of the viral dnBmpR1b-RCAS (B) construct at stage 6. (E) Following injection of dnBmpR1b, a large region of the outer layer of the optic cup is thickened (arrowheads). The infection of the RPE is shown by the expression of RT. (F) Otx2 expression weakens in the outer layer of the optic cup following injection of dnBmpR1b (arrowheads). (G) MMP115 expression is downregulated following inhibition of BMP signalling (arrowheads). (H) Expression of the NR-specific gene Chx10 is induced in the outer layer of the optic cup following viral overexpression of the dnBmpR1b construct (arrowheads). (I) RT expression in the outer layer of the optic cup (arrowheads) following viral infection of the dnBmpR1b construct at stage 7. (J) MMP115 expression is downregulated (arrowheads) in the infected region of the outer layer of the optic cup. Strong MMP115 expression is still observed in the single-layered portion (arrow). (K) RT expression within the proximal RPE (arrowheads) following infection at stage 10. (L) The arrowheads indicate the expression of the NR marker gene Chx10 in the RPE in the parallel section. L, lens; NR, neural retina.